1. Field of the Invention
The present invention relates to an image processing method which is applied to a fax machine, a copying machine and the like, an image processing apparatus which adopts the above image processing method, and a storage medium which stores a control program to control the above image processing apparatus.
2. Related Background Art
Generally, an image which is managed by a fax machine, a copying machine and the like has determined size and shape. This shape is a rectangle extending longitudinally or laterally.
In the currently spreading small fax machines, there are a lot of types that the image is processed in the longitudinal direction (i.e., a portrait orientation). On the other hand, in the currently spreading heavy fax machines, there are a lot of types that the image is processed in the lateral direction (i.e., a landscape orientation).
Thus, in the heavy fax machines having a fax transmission function, there is a type which performs, even if the original is read in the lateral direction, an image rotation process of 90° or 270° to turn the read image toward the longitudinal direction and then fax transmit the turned image.
Similarly, there is a type which performs the image rotation process of 90° or 270°, when the image data is fax received, to turn the output image toward the direction same as that of the image output when the copying machine is normally used.
Further, there is an image reading apparatus which performs the image rotation process of 90°, 180° or 270° to transmit the image data to a connected apparatus such as an image server or the like to which the direction of the image to be transmitted has been defined, or performs the image rotation process of 90°, 180° or 270° to correspond to a user's demand to orient the output images toward a certain direction.
Further, e.g., in a case where the image is printed on a transparent sheet, there is an apparatus which has an image right-and-left or up-and-down reversal function to be able to perform an image reversal process to print a mirror image. In the mirror image, the image has been right-and-left or up-and-down reversed and printed such that, when the printed image is viewed from the back face of this transparent sheet, it becomes the faithful image.
In order to satisfy the demand of such the image rotation process of 90°, 180° or 270° or the image right-and-left or up-and-down reversal process as above, there is an image processing apparatus which achieves such an image rotation/reversal process. In this image processing apparatus, a dedicated memory array or shift register on which data writing and reading can be performed in both the longitudinal and lateral directions is provided, and the direction of the data writing is made different from the direction of the data reading to achieve the image rotation/reversal process.
However, if the dedicated memory array or shift register is used, dedicated circuits for the image rotation and the image reversal are necessary, whereby a memory circuit is complicated as a whole. Thus, a circuit scale becomes large, and thus the cost for achievement rises. Further, the limit of an operation clock frequency capable of operating at high speed is lowered, and the entire circuit has to be designed as exclusive use, whereby expansion and diversion of the circuit are difficult.
Further, the image rotation/reversal process is performed according to a procedure that pixel data representing the image is once stored in an internal memory and then read therefrom. Further, there has been known a method that the pixel data representing the image is not processed at one time, but the entire image is first divided into blocks each having the small number of composite pixels, and the image rotation/reversal process is performed for each of the small image data blocks.
Then, to achieve the rotation/reversal process for the entire image by rearranging the positions of all the image data blocks to which the rotation/reversal process has been performed pro re nata, a rearrangement process is performed for each block by means of an external circuit or software independent of an image rotation and reversal processing apparatus.
The reason of adopting such a structure, i.e., the reason of not performing the rotation/reversal process for the entire image at one time, is that, since the image managed in the fax machine and the copying machine is obtained by reading an original of A4 or letter size at resolution of 200 dpi (dots per inch) or 600 dpi and therefore the total number of pixels constituting the original image is remarkably large, an unrealistic large memory capacity is necessary when the entire image is stored in the memory array, the shift register or a general-purpose memory at one time to perform the image rotation/reversal process.
However, in the case where the rearrangement process is performed for each block by using the external circuit independently of the image rotation and reversal processing apparatus, or in the case where the rearrangement process is performed for each block by using the software, problems occur in processing speed and a parallel operation because of the following reason. Namely, when the rearrangement process is performed for each block, it is necessary to repeatedly perform the reading and the writing for each block on a page memory capable of storing the entire image plural times corresponding to the number of all the blocks. Thus, by repeatedly performing such the processes for all the blocks, it takes excessive processing time corresponding to the time necessary for reading the entire image and the time necessary for writing the entire image in addition to the time necessary for the image rotation/reversal process.
Further, the unit of the above image rotation/reversal process is the entire image. Even if there is a request of the image rotation/reversal process for plural images, it is impossible to simultaneously perform these processes in parallel, and it is also impossible to interrupt the image process being performed. Thus, in this case, since it only waits until the image process which is being performed ends, a priority process or the like which preferentially processes the image to which the process was requested later can not be performed.
Further, since one image rotation and reversal processing apparatus is allocated to one image without fail, even if the number of the image rotation and reversal processing apparatuses is increased, these image rotation and reversal processing apparatuses can not process the one image in parallel, whereby the process can not be completed at high speed.